You can see it on the attached movie.

Code:

    @Override
    public void start(Stage stage) throws Exception {
        VBox vb = new VBox();

        Tooltip tp = new Tooltip();
        tp.setText("text");
        tp.setGraphic(new Rectangle(0, 0, 10, 10));

        Button b = new Button("with tooltip");

        b.setTooltip(tp);

        Slider slider1 = new Slider(0, 100, 50);
        slider1.setShowTickLabels(true);
        slider1.setShowTickMarks(true);

        slider1.valueProperty().bindBidirectional(tp.graphicTextGapProperty());

        vb.getChildren().addAll(b, new Label("Graphic text gap"), slider1);

        Scene scene = new Scene(vb, 300, 300);
        stage.setScene(scene);
        stage.show();
    }